Reverse Osmosis Membrane Fouling Control Patents: Leaders & Trends 2026
A patent landscape review of reverse osmosis membrane fouling control: filing trends since 2017, assignee concentration, IPC composition and the technical claims defining freedom to operate.
Filing growth = 2021 (24 records) → 2024 (13); 2024 is the last year we treat as complete. Top-5 share = the 5 largest assignees ÷ all 851 records in scope (CR5), not the ranked leaders only.
What this landscape covers
Reverse osmosis membrane fouling control spans chemical pretreatment, membrane surface modification, cleaning formulations and biofouling inhibition — all aimed at the same operational problem: flux decline over the life of a membrane system. This landscape maps 851 published records filed between 2015 and 2026 against IPC classification, assignee identity and filing office to show where claim density is highest and where activity has thinned. Patent families, not raw document counts, are the fairer comparison unit because they neutralise aggressive continuation and multi-jurisdiction filing behaviour by any single applicant.
The dataset draws on titles, abstracts and claims matched against reverse osmosis membrane terminology combined with fouling, biofouling, flux decline and fouling resistance language, restricted to separation-process and water-treatment IPC classes. Coverage runs through the 2026-08-31 cut-off, though the most recent one to two years understate true filing activity because publication lags filing by roughly 18 months.
Filing trend, technology mix and concentration
Three views of the same 851-record dataset: how filing volume has moved year over year, which IPC subclasses carry the claim density, and how concentrated ownership is among the ranked assignees.
Filing trend, 2017–2026
Filings rose from 29 in 2017 to a peak of 64 in 2018, then eased. Using only complete years, 2021 filings of 24 fell to 13 by 2024 — a 46% decline over that span. 2025 and 2026 counts are still incomplete due to publication lag and should not be read as a continued drop.
Publication lags filing by roughly 18 months, so 2025 onwards are still filling in. Growth rates on this page therefore end at 2024; running them to the last bar would understate the field.
IPC subclass composition
B01D (separation processes, including filtration) appears on 89.0% of the 851 records and C02F (water and wastewater treatment) on 74.0%, confirming this is overwhelmingly a filtration-and-treatment-process field. Smaller shares sit in B01J and G01N (2.7% each), C11D detergents (2.5%), A01N biocides and A61L sterilising agents (2.0% each), and G01R electric/magnetic measurement (1.2%) — the analytical and sensing edge of the field. Because records can carry multiple IPC codes, these shares sum to well over 100% of the record total.
Shares are the percentage of the 851 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Reverse Osmosis Membrane Fouling Control Patent Landscape with Eureka
This page is one run against one query. Ask Eureka your own question about reverse osmosis membrane fouling control patent landscape and every answer comes back with the patent numbers behind it.
Try EurekaMost-cited prior art and a recent representative filing
Silica fouling inhibition method and silica fouling inhibitor for reverse osmosis membrane system
A silica fouling inhibition method for a reverse osmosis membrane system in which an acrylic acid-based polymer and/or a maleic acid-based polymer is present in the treated water together with a combined chlorine-based and/or bromine-based oxidizing agent. The inhibitor itself is specified as a copolymer of acrylic acid and 2-acrylamide-2-methylpropanesulfonic acid, and/or a terpolymer adding N-substituted acrylamide, again paired with the combined oxidizing agent.Filed by Kurita Water Industries, published 2025-03-27 — illustrates the current claim style around silica-specific fouling, combining a polymer dispersant class with an oxidizing biocide component rather than either alone.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US5670053A | Purification of gases from water using reverse osmosis | 194 |
| 2 | US5244579A | Transportable reverse osmosis water purification unit | 160 |
| 3 | US6177011B1 | Composite reverse osmosis membrane having a separation layer with polyvinyl alcohol coating and method of rev… | 137 |
| 4 | US4496470A | Cleaning composition | 130 |
| 5 | US4988444A | Prevention of biofouling of reverse osmosis membranes | 120 |
| 6 | US20110005997A1 | Hybrid TFC RO membranes with nitrogen additives | 119 |
| 7 | US6908546B2 | Apparatus and method for producing purified water having microbiological purity | 101 |
| 8 | US4740308A | Membrane cleaning process | 100 |
| 9 | WO2008091453A1 | Method to control reverse osmosis membrane biofouling in drinking water production | 98 |
| 10 | US4176057A | Method and apparatus for recovering liquid and solid constituents of water solutions containing sparingly sol… | 79 |
Citation counts favour older filings that have had more time to accumulate citations within the searched corpus — they signal influence on subsequent filing activity, not current commercial importance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Reading the concentration, trend and IPC figures together points to where claim space is crowded, where it has thinned, and what that implies for a new filing.
Ownership is concentrated but not locked up
The leading assignee alone accounts for 66 records, and the top 5 combined for 210 — 24.7% of the full 851-record set. That leaves three-quarters of filings spread across the remaining 95 ranked companies plus unranked entrants, which is a long tail rather than a closed field.
Activity has cooled from its 2018 peak
Filings peaked at 64 in 2018 and, on the last fully-observable window, fell from 24 in 2021 to 13 in 2024. That is a genuine decline over complete years, not an artefact of publication lag, though 2025-2026 counts will still revise upward.
Separation-process claims dominate the field
B01D and C02F together cover the large majority of records, meaning most claim activity sits on membrane and treatment-process mechanics rather than adjacent chemistry. The smaller classes — biocides, sterilising agents, detergents, sensing — sit at 2-3% each, which is where narrower, less contested claim space tends to remain.
Filing offices lean toward Asia and the US
Japan leads receiving offices with 149 records, ahead of the United States at 137 and China at 106, with WIPO PCT filings at 82 and EPO at 79 indicating meaningful multi-jurisdiction strategy among the more active assignees.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to reverse osmosis membrane fouling control patent landscape, with the prior art for and against each one.
Where to take this analysis
The figures above describe the field as filed; deciding what to do about it requires drilling into specific claims and specific assignees.
Check freedom to operate on a specific formulation
If a fouling-control approach combines a polymer dispersant with an oxidizing biocide, the recent Kurita filing and its neighbours are the first claims to check against.
Explore claim scope in EurekaTrack the long tail beyond the ranked leaders
With three-quarters of records held outside the top 5 assignees, new entrants and smaller players are filing actively — worth monitoring rather than assuming the field is settled.
Set up assignee monitoring in EurekaWatch for the 2025-2026 revision upward
Because publication lags filing by roughly 18 months, current filing volume is understated in the most recent years shown here; re-check this trend in a future cut before concluding the field is shrinking.
Run an updated search in EurekaCommon questions on this landscape
The leading assignee in this dataset holds 66 of the 851 records in scope, with the top 5 assignees combined accounting for 210 records, or 24.7% of the total. That leaves the majority of filings — over 75% — spread across a long tail of other companies, so no single organisation controls the field outright. Anyone assessing freedom to operate should still check the leader's claims closely, since 66 records from one assignee is a meaningful concentration of prior art in a specific technical niche.
Using only complete years, filings fell from 24 in 2021 to 13 in 2024, a 46% decline, after peaking at 64 in 2018. That is a real cooling trend over the observable window. However, 2025 and 2026 figures are still incomplete because publication typically lags actual filing by around 18 months, so it would be premature to call the field in permanent decline based on the most recent two years alone.
The large majority of records sit in B01D (separation processes including filtration), at 89.0% of the 851 records, and C02F (water and wastewater treatment), at 74.0%. Smaller shares appear in B01J and G01N (2.7% each), C11D detergents (2.5%), A01N biocides and A61L sterilising agents (2.0% each), and G01R sensing (1.2%). Because a single record can carry multiple IPC codes, these percentages sum to more than 100% of the record total, which is expected and not an error.
Japan is the leading receiving office with 149 records, followed by the United States at 137 and China at 106. WIPO PCT filings reach 82 and the European Patent Office 79, with South Korea at 51 — a pattern that suggests the more active assignees are pursuing multi-jurisdiction protection through PCT and EPO routes rather than filing in a single home market.
A 2025 filing from Kurita Water Industries (US20250099916A1) claims a silica fouling inhibition method combining an acrylic acid-based and/or maleic acid-based polymer with a combined chlorine-based and/or bromine-based oxidizing agent present in the treated water. The inhibitor composition itself is specified down to a copolymer of acrylic acid and 2-acrylamide-2-methylpropanesulfonic acid, optionally extended to a terpolymer with N-substituted acrylamide. This illustrates the current style of claim in the field: pairing a specific polymer dispersant chemistry with a specific oxidizing biocide class, rather than claiming either mechanism alone.
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Disclaimer. This page is generated from Patsnap Eureka data drawn from a limited snapshot of global patent and scientific-literature records, and is provided for general information and reference only.
Patent data carries inherent limitations: recent filings (typically the most recent 18–24 months) are under-counted due to standard publication lag; counts may be reported at either a patent-family or a patent-record basis and are not always directly comparable; classification, applicant-name, and citation data may contain errors, duplicates, or omissions; and the underlying search query defines and constrains the scope shown. As a result, the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
Nothing on this page constitutes an exhaustive prior-art, novelty, freedom-to-operate, or validity search, nor does it constitute legal, financial, investment, or professional advice, and it should not be relied upon as such. Any patent, commercial, or strategic decision should be verified independently and reviewed with qualified patent, legal, and domain professionals. Patsnap makes no warranties, express or implied, as to the accuracy, completeness, or fitness for any particular purpose of the information presented.
Machine translation. Assignee and organisation names originally recorded in Chinese, Japanese or Korean have been rendered into English by an AI translation step so that the tables stay readable. These renderings are best-effort and may not match a company’s registered English name; the original name is what the underlying patent record carries, and it is what any Eureka query launched from this page uses.